Rectification of printing-plates



E. E. NQVOTNY.

HECTIFICATION OF PRINTING PLATES.

APPLICATION HLED AUG.6,'1918.

. 1,377,515 Patentd May 10,1921.

UNITED STATES PATENT OFFICE. I

EMIL E. NOVOTNY, or PHILADELPHIA, PENNSYLVANIA, ASSIGNOR T J. STOGDELLs'roxns, or MOORESTOWN, NEW JERSEY.

nncmrrcarroiv on PRINTING-PLATES T 0 all whom it may concern:

' Be it known that I, EMIL E. Novo'rNY, a

citizen of the United States, .residing at Philadelphia in the county ofPhiladelphia and State of Pennsylvania, have invented new and usefulImprovements" in Rectificationof Printing-Plates,of which the followingis a specification.

This invention relates to the manufacture of printing plates and hasparticular a-pplication to the rectification of molded printing platesand such as are made from a plastic material as bakelite, condensiteorother synthetic resin. p

In carrying out my lnventlon-it is my purpose to provide a rapid andready method ofleveli'ng printing plates and of incorporating thereinthe required regulari- I ties and irregularities such as are practisedin the printing art and usually termed make ready. Half-tones andoriginal type matter when assembled in a type form or chase frequentlypresent irregularities in height, or in some instances possessconations.

caved or rounded or imperfect type faces due to wear incident to use inprinting oper- Of course it is desirable that a printing plate producedfrom a matrix made from such a body'of type or from such printing and itis desirable to incorporate this make-ready in the molded plate'beforeitis placed on the'press. In electrctyping' it is the practice toeliminate these errors or irregularities in the plate by pounding the"back of the electrotype while its face is in contact with thelevelsurface plate,'but this method of rectifyingthe plate isunsatisfactory and does not permit the attainment of accuracyin'the'cross-s'ectional thickness of 3 the platenor does it allowofthe'introduction of make-ready corrections into the body of the plate.

In plasticplate making, or where print i'ng plates 'are'made by means ofa moldlng I operation, it is impossible to pound out 'jirregularitiesas'is done with'electrotypes and it is therefore desirable to" resorttoother means to secure the necessary rectifi-x plate.

.cation of theplate. In the manufacture of synthetic reslnous printingplates, such as Specification of Letters Patent. Patented lu y 10 1921'Application filed August 6, 1918. Serial No: 248,648; i i

those made from bakelite or condensite, I

' have found that by using a body material which is not compressedbeyond its elastic limit, but which may be further slightly compressedafter the printing characters havebeen molded on the face of the plate,such a plate may be rectified or corrected in such a manner as to obtainuniformity in the height of the letters as well as uniformity in thecross section of the plate, and to employ make-ready in therectification process. These necessary and desired corrections may beaccomplished because of the fact that in themolding of a plastic plateunder heat and pressure, the plate is subjected to a molding operationfor just asuflici'ent length of time to bake a hard film or skin on eachface of the plate, while the interior of theplate will remainrelativelysoft when compared with the exterior surface.

heated condition and subjected to pressure between the level platens ofthe press so as tion ofthe plate, the interior portion yieldingsufficiently without lateral flow or spread, to accommodate orcompensate for the backward pressure of the hardened irregularity of thesurface'sections of the In the accompanying drawings Figurel shows acrosssectio'nal view of a printing 'press'iplate composition between twoplatens of asuitablepress preparatory to rectifying the platebylevelingand the introduction of make-ready.

Fig. 2 is a cross sectional view of another form of printing plate whichmay be corrected in accordance with my method.

Flg. 3 1s a View partly, n elevation and partly in section showing a.printing plate Theresult' will be that such a plate may be placed in apress while in a tolevel the printing surface, as well as the back oftheplate by forcing the uneven portions or irregularities of thehardenedskin back toward the relatively soft interior porcoated onitsprintiiig surfaces with a waxy "substance, the non-printingportionsof the plate being exposed to the action of a sand blast for the purposeof deepening the same.

Referring now to the accompanying drawings indetail: The letter Aindicates the lower hollow platen of the press while BY designates theupper hollow platen thereof,

7 interior portion 6 of the plate.

with these plates having steam inlets l and steam outlets 2. Upon thelevel face of the thereof and the upper printing face 5 are relativelyharder than the intermediate or This occurs in the baking operation inmolding the plate, because the outer surfaces of the plate will bake orcook until a hard shell like skin or film is formed around the plate,this synthetic resinous material being a poor conductor of heat so thatthe outer surface portions will bake more readily than the interior ofthe plate body. If it be desired to correct such a plate it may bepreliminarily heated either in a separate oven, or in the press and isthen placed as shown in Fig. 1 upon the lower plate, and with thebearers arranged at opposite sides of the plate to limit the closing ofthe platens. If it is not desired to incorporate separate make-ready inthe plate the platens may be simply closed to force the back of theplate fiat against the face of the bottom platen of the press and toforce such irregularities as may appear in the type surface of the platedown toward the interior of the plate, the material of the interior ofthe plate being displaceable, or capable of yielding sufficiently topermit of this so that the high sections of the type surface will ,bedepressed or sunk to the proper level thereby enabling a plate ofuniform thickness and height of type to be made.

If it be desired to form a printing face of the plate with certainregularities or irrcgularities to compensate forpress errors or for thepeculiarities of a particular press, suitable negative make-ready suchas is shown at 7, and which is well known in the art, may be laid orplaced upon the printing surface of the plate in proper coincidence withthe type sections of the plate which are to be corrected by tnismake-ready, and the platens of the press may then be closed to force themake-ready against the sub 'acent printing surface of the plate, and ofcourse these sections will be forced or sunk toward the interior of theplate and the necessary correction thereby obtained.

In Fig. 1 it will be noted that the back of the plate C is substantiallysmooth'while in Fig. 2 I have shown a modified form of the plateindicatedby C and in this instance the bottom face of the plate isformed with a field or cone shaped dots, or is pitted as shown at 8, thepurpose of so forming the back face of the plate being to allow forcompression from the back of the plate inward toward the center thereof,aswell as toward the face of the plate, thus permitting of more leewayin the leveling and correction of the plate than can be obtained wherethe back of the plate is smooth in the first instance as is shown inFig. 1. Therefore in the preparation of my printing plates I prefer, ininitially making the plate, that is to say prior to its correction, tomold the plates with dots, pits or depressions in the back face thereof.Of course when make-ready is used in making the correction suchmake-ready is removed after the rectification of the plate has beenaccomplished. This method of leveling and of treating the plates withmake-ready enables me to manufacture plates from type matter which isnot of proper printing standards, and also permits of the levelingoperation being accomplished in a simple and speedy manner at the timeof incorpo- .rating the make-ready and also provides for obtaining aplate of a predetermined level and of uniform thickness. From a printing standpoint it enables me to make a printing plate which requires nomakeready when applied to the printing press and enables the pressman toobtain a maximum production from a printing machine with little or nodelay in machine attention or activity.

In some instances the leveling of the plate may decrease the depth ofthe. nonprinting parts of the printing surface of the plate and thenagain on occasions itmay be desired to obtain greater depth innonprinting parts. Under such conditions I may apply to the printingsurface of the plate a greasy or waxy paste 9 composed for instance ofbeeswax and rosinoil, the. application of the paste being madebymeans ofa printing roller or cloth swab, or any other suitable tool.

' low, non-printingparts in certain'types of printing plates.

What I claim is: 7 I I v The herein described method. of rectifying amolded printing plate madefrom a plastic substance, which consists infirst molding a plate under. heat, and pressure for a suflicient lengthof time to obtain relatively hard, skin-like face and back portions Thepaste is applied onlyto the printing portions of the printing plate andprovide a printing surface for the face portion, the interior portion ofthe plate remainin relatively soft and capable of limited displacementunder subsequent pressure, and subsequently subjecting said plate whilein a heated condition to pressure to force irregularities in the hardprinting face inward in the body of the plate and my hand.

in opposition to the soft displaceable in-.

terior portion of such plate, and While 10 maintaining the back portionofthe plate in a substantially flat and level condition.

In testimony whereof I have hereunto set I EMIL E.;NOVOTNY.'

